BioChem Lecture 3_Enzymes Flashcards
(16 cards)
Define the mechanisium of oxidoreductases
Oxidoreductases are a class of enzyme that cause the oxidation of a substrate. This is typically accomplished through the transfer of two electrons and protrons from the substrate to NAD+ which forms NADH and H+
Define Transferase
A transferase is an enzyme that catylize the transfer of a functional group from one substrate to another substrate
Define hydrolases
A hydrolases is a class of enzymes that cleave bonds through the introduction of a water molecule
Define Lyases
A lyases are a class of enzyme that cytalize the cleavage of C-C C-S and some C-n bonds
Define Isomerases
Isomerases is a class of enzyme that move a functional group from one location on a substrate to another location on the same substrate.
Define Ligases
Ligases are a class of enzymes that catalyze the formation of bonds between C, S, O, and N. It requires the use of ATP. it is essentially a reverse Lyases
Synthase vs Synthetase
Synthase joins two molecules without the use of ATP
Synthetase joins two molecules with the yse of ATP
Phosphatase vs Phosphorylase
Phosphatase uses H2O to remove phospho group (thus it is a hydrolase
Phosphorylase adds Pi to a molecule to give a phosphoralated product
Oxidase vs oxygenase
Oxidase transfers things to O2 without incorporating it into the main structure
Oxygenase use one or both of the oxygens in the main structure
How do enzymes work
They lower the energy of activation for chemical reactions by holding substrates in energetically favorable positions
What factors effect reaction velocity? How?
Tempurature, pH, substrate consentration
Explain Michaelis Menten enzymes vs Allosteric enzymes
Michaelis-Menten enzymes show a hyperbolic relationship between reaction velocity and substrate consentration.
Allosteric enzymes show a sigmodial relationship between substrate consentration and reaction velocity.
What is Km and what does it tell us
Km is a messuerment of the affinity of a substrate for its enzyme. Km is the x value that equates to the y value of Vmax/2. Note a small Km represents a higher affinity (Vmax is reached a relativly low consentrations of substrate).
What do the x and y intercepts equal on a Lineweaver-Burk plot?
x intercept = -1/Km
y intercept = 1/Vmax
Noncompetitve vs competitive inhabition
CI binds to the active site of an enzyme and thus competes with S. NI bind to a site away from the active site but cause a conformational chage that prevents the enzyme from binding substrate
Think through how NI and CI change kenetics of a rxn, why the changes occure and how that alters a Lineweaver-Burk plot
see slides 22 and 23 if needed.
